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Lathe tools

Carbide or index?

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David Smith 4227/08/2018 19:58:29
5 forum posts

sorry if this has been asked to death! Can anybody recommend a good quality make of lathe tool. Think I may have bought some rubbish? I have little experience but I am keen to learn. Would be grateful for any input.Thanks in advance. Manchester based.

Brian H27/08/2018 20:11:12
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2312 forum posts
112 photos

Hello David, a lot depends on what lathe you have and what materials you are likely to be using.

Can you say more about the tools that you have bought?

Carbides are good for getting under the hard skin on cast iron but otherwise they need to be taking a reasonable cut, not just taking off a couple of thou.

Index tools are really the same thing but available in preset shapes so that a worn tip can be replaced without having to set up again from the beginning.

Two that you haven't mentioned are hight speed steel which can be had ready ground but can be sharpened on a bench grinder (with the correct wheel) or can be ground to suit the shape of the job.

Similar to that is old fashioned tool steel such as the stuff that files are made of. This can be softened, filed to shape and then re-hardened and tempered.

Im sure someone will be along shortly with more but the initial questions remain; what is your lathe and what materials will you be working?

Brian

Vic27/08/2018 20:19:06
3074 forum posts
8 photos

He’s got a Boxford ME10 Brian.

You’ve not given much information on what type of stuff you intend to make but here’s a couple of ideas.

This type of tool holder is very good and cheap to run on small pieces of HSS once you have the holder.

**LINK**

Or you could go for insert tooling. Just one supplier.

**LINK**

SillyOldDuffer27/08/2018 21:43:41
Moderator
8698 forum posts
1967 photos
Posted by David Smith 42 on 27/08/2018 19:58:29:

... Think I may have bought some rubbish? ...

Possibly, but more likely if you're a beginner, it's something else, for example:

  • Tool at wrong height
  • Depth of cut too deep or too shallow
  • rpm too high or too low
  • Feed rate too high or too low
  • Material obnoxious! Quite a lot of scrap and DIY store metal is horrible and won't machine well. (Soft sticky aluminium, ornamental steel, stainless steel, copper, and hard steel & other alloys are all best avoided.)
  • Wrong tip shape for the material & type of cut.

Another issue might be blunt brazed carbide tipped tools looking like these. I don't get on with this type of tool compared with HSS or carbide inserts. But the big booby trap is some (not all) are supplied unsharpened and you need a special grinding wheel to touch them up before use.

As a beginner HSS sets like this example arrive ready to go and the knives are easily kept in shape with an ordinary grinder. With practice it's possible to grind HSS blanks to shape yourself. Not everyone has the knack of sharpening HSS and carbide indexed insert tooling might be easier.

Can you explain in more detail what you have and what the problem is? A photo of the tool against the work would be good. If you're self-taught (as I am), be prepared to experiment. Not rocket science exactly, but there's a fair amount to learn before you get good results.

Dave

Vic27/08/2018 22:00:51
3074 forum posts
8 photos

You may well be right about the brazed carbide Dave, I think they’ve caught a lot of people out. smiley

colin hawes28/08/2018 11:37:31
558 forum posts
18 photos

HSS tools are the most economical way to go for a beginner and will machine all the metals you are likely to use in model making but carbide tips are very useful to machine cast iron at a higher speed. Colin

Peter G. Shaw28/08/2018 17:26:55
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1421 forum posts
44 photos

I have tried two sets of brazed carbide tips - with a total lack of success! Ok, some of that, maybe all of it, may be down to me. In particular, I had a parting off tip break off the first time it was used, and a somewhat larger parting off tip create nothing but chatter. Otherwise, I seemed to spend more time re-sharpening than using.

I have tried a few indexable inserts with some success. Probably the biggest problem being that the tips I bought are not wide enough to give a smooth surface, ie they are producing a very fine thread.

I find HSS generally works well for me, and I can obtain smooth surfaces at low cutting rates. Ok, ok, I know that goes against conventional wisdom, but it works for me.

I have also experimented in converting old files (high carbon steel/tool steel) into lathe cutting tools. These do work, but do not seem to last too long before requiring re-sharpening. I think I probably need to experiment more with angles.

In essence then, I would recommend HSS initially, with indexable carbide tips second. But of course, you will need a grinder to (re)sharpen the HSS. But against the cost of a grinder, HSS is a lot cheaper than indexable tips and their holders, but indexable only need setting up once - swings and roundabouts.

One other thing. Don't bother with those sets one can buy. Whilst they give a good selection of tools, you will find that for the majority of work, you will use one tool - the right hand knife tool. Second, after a while, is likely to be the boring tool, with much, much later, the third being the dreaded parting off tool. The other tools might never be used. Also, my experience is that the parting off tools in the sets I have bought have been much too wide leading to chatter - my lathe has to have tools no more than 2mm wide, my present tool, an old file, being 1.84mm wide.

Cheers,

Peter G. Shaw

David Smith 4228/08/2018 19:19:52
5 forum posts

Many thanks for your help. Much appreciated.

John Reese28/08/2018 20:45:24
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1035 forum posts

I second Vic's suggestion of he diamond tool. I made myself a pair, right and left, some time ago and find them most useful. Regrinding the tool bit is quite simple: a 30* grind on the diagonal of the bit.

I do own a set of indexable tools from Glanze. They use an 80* diamond insert. Two of the tool holders allow use of the obtuse corner of the insert. I am quite happy with the set.

https://www.glanze.co.uk/acatalog/Boxed_Sets_of_Lathe_Turning_Tools.html

Peter G. Shaw28/08/2018 21:02:10
avatar
1421 forum posts
44 photos

Just goes to show, doesn't it - I did not answer David's original question, instead I gave my opinions.

OK here goes.

A few years ago, I bought some tips and a suitable holder from Greenwood Tools for use on my milling machine. I have been surprised just how good they were. I can only assume that the tips are Greenwoods NJ17 material. As a result, when I needed some tips for some SCLCR/L holders I had bought in error, I used Greenwoods tips with the results as described in my post above. The SCLCR/L holders came from Shop APT.

Please note, I have no connection with either of these firms other than as a satisfied customer.

Cheers,

Peter G. Shaw

Howard Lewis17/11/2018 23:30:52
6116 forum posts
14 photos

For almost all external turning I use a Tangential Tool. Made the first one, for 1/8 toolbits,and was so impressed that i bought the Eccentric Engineering one.

Replaceable carbide tips are only used on the boring bar, or when chipped, the 100* corners for external roughing.

Sharpening the diamond tool is an absolute joy, just one face on an ordinary wheel.

Parting is with an OLD HSS blade., (secondhand when i was given it thirty plus years ago) Found that dig ins with a replaceable carbide tip one was a very expensive game.

Howard

fat fingers again!

Edited By Howard Lewis on 17/11/2018 23:31:55

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